In article handling systems such as storage and retrieval crane stacking systems, it has become common to store and retrieve articles in response to a command from a control center such as a computer. For example, in a crane type system, a crane is movable horizontally along a track between two rows of storage racks, each rack having vertical and horizontal storage spaces. The crane is provided with a table movable laterally to and from the storage spaces as well as vertically.
When a computer is utilized to control the crane, the computer is programmed to properly deliver and pick up articles from the storage spaces. More specifically, the computer controls the movement of the crane horizontally and the table vertically and horizontally on the crane. However, in setting up the system in the field and in use thereof, it is often desirable to change the program to accommodate changes in dimensions occurring during erection due to wear. In making such changes, the services of a highly skilled electronically trained programmer are required.
More recently, to avoid the problem of festooning large numbers of wires to the central computer, it has become desirable to utilize a computer on board the crane using memory modules of the read-only type. Such memory modules are either erasable or non-erasable. Where they are non-erasable, in order to change the memory, they must be replaced by a newly programmed memory. Where they are erasable, it is necessary to completely erase the memory and then re-program the device with the corrected information. In any event, special apparatus and skill is required.
It is an object of the present invention to provide an article handling system such as a storage and retrieval crane system utilizing a re-programmable memory which does not require skilled electronically trained persons; which is manually operated to erase part or all and re-program selectively a function; which utilizes a compact, easily manufactured module.